As is well known to those skilled in the art, a remote center compliance (RCC) device supports a part, or other member to be positioned, for adjustive translatory and/or rotational movement about a center of compliance, disposed distal from the device itself, in response to forces and/or moments imposed upon the supported member at the remote center. Although capable of various other utilizations, RCC devices frequently are employed to compensate for misalignment between mating parts that are to be interconnected during an assembly or similar operation performed by a robot or other automatic machine.
In their most commonplace form, RCC devices consist of primary and secondary frame members interconnected by a plurality of angularly extending or "focalized" compliant members, and their projected centers are incapable of positional adjustment. Another type of RCC device, disclosed in U.S. Pat. No. 31,999, may be constructed so as to possess a long slender configuration, as opposed to the relatively bulky construction of the focalized devices, and further may be adjusted so to vary the location of the remote center projected by the device. In contrast to these RCC devices of purely mechanical types, it has also been proposed to provide misalignment compensating devices, albeit not necessarily ones that project a remote center of compliance, that employ fluid means in their operation. For example, U.S. Pat. No. 4,458,424 discloses the use, in what is basically an RCC device of the bulky mechanical "focalized" kind, of fluid-filled elastomeric spheres in lieu of solid elastomeric elements as the connectors between the primary and secondary frame members. By varying the pressure within individual ones of the spheres, the location of the remote center may be varied, and compensation may be made for the "sag" undergone by the device when it is used in a horizontal orientation. U.S. Pat. No. 4,571,148 discloses a positioning device having actuators operable by compressed air or other gas whose flow is actively controlled in response to sensed displacements of a device component. As is recognized in the patent itself, the "active" device of the patent differs greatly from conventional RCC devices that do not require any sensing means to detect misalignments, nor any motors or other actuators to compensate for them.